<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style type="text/css">
        * {
            margin: 0;
            padding: 0;
        }

        ul {
            list-style: none;
        }

        .wrapper {
            width: 1000px;
            height: 475px;
            margin: 0 auto;
            margin-top: 100px;
        }

        .tab {
            border: 1px solid #ddd;
            border-bottom: 0;
            height: 36px;
            width: 320px;
        }

        .tab li {
            position: relative;
            float: left;
            width: 80px;
            height: 34px;
            line-height: 34px;
            text-align: center;
            cursor: pointer;
            border-top: 4px solid #fff;
        }

        .tab span {
            position: absolute;
            right: 0;
            top: 10px;
            background: #ddd;
            width: 1px;
            height: 14px;
            overflow: hidden;
        }

        .products {
            width: 1002px;
            border: 1px solid #ddd;
            height: 476px;
        }

        .products .main {
            float: left;
            display: none;
        }

        .products .main.selected {
            display: block;
        }

        .tab li.active {
            border-color: red;
            border-bottom: 0;
        }
    </style>
</head>

<body>
    <div class="wrapper">
        <ul class="tab">
            <li class="tab-item active">国际大牌<span>◆</span></li>
            <li class="tab-item">国妆名牌<span>◆</span></li>
            <li class="tab-item">清洁用品<span>◆</span></li>
            <li class="tab-item">男士精品</li>
        </ul>
        <div class="products">
            <div class="main selected">
                <a href="###"><img src="imgs/guojidapai.jpg" alt="" /></a>
            </div>
            <div class="main">
                <a href="###"><img src="imgs/guozhuangmingpin.jpg" alt="" /></a>
            </div>
            <div class="main">
                <a href="###"><img src="imgs/qingjieyongpin.jpg" alt="" /></a>
            </div>
            <div class="main">
                <a href="###"><img src="imgs/nanshijingpin.jpg" alt="" /></a>
            </div>
        </div>
    </div>

    <script>
        //第一步,获取事件源
        let lis = document.querySelectorAll('.tab>li');
        let divs = document.querySelectorAll('.products>div');
        //console.log(lis, divs);

        //第二步,让lis foreach循环,排他增加"active"的类名
        lis.forEach(function (li, i) {
            //li是每个元素,i是每个元素的下标
            li.onmousemove = function () {
                //给每个元素添加鼠标移动事件
                lis.forEach(function (a) {
                    //二次遍历,去掉每个元素的"active"类名
                    a.classList.remove('active')
                })
                //排他思想,给特定的元素添加"active"类名
                li.classList.add('active')

                //上排lis处理完,然后到下面的divs
                //也是一样foreach循环去掉元素的"selected"的类名
                divs.forEach(function (item) {
                    item.classList.remove('selected')
                })
                //最后再根据上面lis 的foreach得出来的i下标
                //再根据对应的下标来给divs添加"selected"
                divs[i].classList.add('selected')
            }
        })


    </script>
</body>

</html>